Transformer



Dec. 30, 1930. J. c. DALEY ET AL 1,786,422

TRANSFORMER Fi led Nov. 11, 1927 2 Sheets-Sheet 1 Patented Dec. 30, 1930own-:1) sTATEs PATENT OFFICE JAMES C. DALEY AND EDWIN G. QODDARD, 01fCHICAGO, ILLINOIS, ASSIGNORS TO JEF- FERSON ELECTRIC MANUFACTURINGCOMPANY, OF CHICAGO, ILLINOIS, A CORPORA- TION OF ILLINOIS TRANSFORMERApplication filed November 11, 1927. Serial No. 232,523. 1

This invention relates to improvements in transformersand pertains moreparticularly gaseous providing a relatively high or increased. ini-'tialor starting voltage and thereafter a re duced or relatively lowvoltage for the decreased load following the greater initial starting orbreakdown load. I v While the invention has particular utility inconnection with gaseous tubes and the like, it is to be understood thatthe invention is not limited to a particular use or purpose but maybeemployed for ignition purposes or wherever suitable or desired, asforexample, wherever a' relatively high initial voltage is desired followedby a reduced or relatively low voltage for a decrease in load.-

According to the present invention, we provide the transformer with ashunt path which shunt path has a reluctance "higher than the reluctanceof the secondary core, so that upon initial energization of the primarywinding substantially the entire magnetic 80 flux spreads through thesecondary core and a relatively high initial voltage is induced in thesecondary winding. Upon energization of the secondary winding theopposition set up thereby, increases the reluctance oft-he secondarycore beyond the reluctance of the shunt path, whereupon the reluctanceof the shunt path is overcome and at least a part of the primary fluxleaks through the shunt and threads back and through the primary field.The flux threading through or intensity of the secondary field istherebyreduced with an accompanying reduction in the electromotive forceand voltage in the secondary winding; The device may be designed topropor tion, as desired, the leakage back through the shunt with respectto the flux which'threads through they secondary core, by means, ofwhich the voltage which follows the relatively high initial voltage maybe reduced as desired and effectively controlled.

reduced and in which undesirable variations tion are the provision of agenerally im- We further find that by reducing the cross section of thesecondary core below the cross section of the primary core, a naturalstricture is produced between the main and secondary fields whichstricture when disposed on the secondary side beyond the shunt, with theshunt on the primary side of the core with reference to the reduction insection produces a natural shunting tendency. We find that the smallercross section of the secondary core enables a reduction in the sectionof the shunt path, which reduction in the section of the shunt reducesthe space between the rimary and secondary windings and enables reducingthe dimensions of the entire device and increasing the size of theprimary and secondarywindings. This increases the compactness andefiiciency of the device and the smaller section of the secondary coreappears to saturate'the secondary core to provide a 7 high inducedinitial voltage, the opposition set up upon energization of thesecondary winding apparently increasing the reluctance of the secondaryfield and decreasing the amount of flux thereafter required to saturate7 the same.

The present invention also preferably employs a butt joint or gapbetween the legs of the primary and secondary cores, which butt joint orgap is preferably disposed adjacent the end of the secondary winding andon the secondary side of the shunt and provides an additionalretardation to the flux between "the primary and secondary cores.

The invention further provides a self-contained, enclosed shunt and adevice in which the effect thereon of external magnetic materialsadjacent the device, such as metallic housings supporting brackets, orthe like, is

in the action or operation of the device, such as might be caused bydifferent external magnetic materials are avoided.

Still further objects of the present invenproved and simplifiedconstruction that may be economically produced and which constructionmay be standardized for devices of different sizes and for devices ofdifferent types.

We reserve, of course, the right to correct or supplement thetheory ofactlon and advantages should it at any time become desirable.

The invention is illustrated in the accompanying drawings, in whichformer selected for illustration.

Figure 1 is a top plan view of a transformer embodying the invention;

Figure 2 is a side elevational view of the transformer shown in Figure1;

Figure 3 is an end view;

Figure 4 is a sectional view taken on the line 44: of Figure 2;

Figure 5 is a transverse section taken 0 the line 55 of Figure 1; and

Figure 6 is a wiring diagram of the trans- Referring to the drawings thetransformer shown is of the shell or confined type having a main core 5and a secondary core 6.

The main and secondary cores 5 and 6 each comprises a plurality ofsimilar stacked laminations 8, said laminations 8 being suitably shapedto form a central extension around which the transformer coils orwindings are wound and outer legs which form a laminated iron ring orenvelope surrounding or enclosing the coils. WVhile the laminations 8may be of any desired or preferred form or configuration they arepreferably and are shown as of Eshaped form, each having a central orintermediate leg 9 and outer legs 10 extending from a connecting base 12with coil or winding receiving spaces 13 formed between the central andouter legs of each lamination, these spaces 13 opening from one end ofeach core stack and being closed at the other end by the base portion 12of the E-shaped laminations.

The transformer is assembled with the end of the primary core 5 fromwhich the spaces 13 open, in opposition to the corresponding end of thesecondary core 6 and with the central and outer legs 9 and 10 inregister transformer coils or windings may be employed. For the purposeof illustration we have shown a single primary coil or winding 16 woundaround or encircling the central leg 9 of the primary core 5 through thespaces 13 and between the central leg 9 and outer legs 10 of the primarycore. The primary winding 16 is shown as provided with a terminal lead18 for connection with one side of the source of current and with high,me-

dium and low leads or taps 20, 21 and 22 respectively, for connectionwith the other side of the source of current depending upon the voltagerequired by the gaseous tube or other device connected across theterminals of the secondary winding. The particular manner of connectingthe source of current across the primary winding and the number of leadsor connections therefore may, of course, be varied widely within thescope of the present invention.

While it is to be understood that there may be a plurality of secondarywindings and that any suitable or preferred arrangement thereof may beemployed, we have, for purposes of illustration shown a single secondarywinding 25 wound about or encircling the central leg 9 of the secondarycore 6 with the turns of the secondary winding passing through thespaces '13 and between the central leg 9 and outer legs 10 of thesecondary core. The secondary coil 25 is shown as being sectionalizedcentrally at 26 with the sections connected as illustrateddiagrammatically at 27 in Figure 6 and grounded through the centralconnection 27 as shown at 28. The secondary winding 25 is provided withterminal leads 29 and 30 for connection across the gaseous tube or otherdevice which is to be supplied from the secondary winding of thetransformer. A gaseous tube 100 is shown more or less diagrammaticallyin Figure 6 as connected across the leads 29 and 30.

It is to be understood, of course, that the turns of the primary andsecondary windings are insulated from each other and from the magneticcore as desired and in any suitable or preferred manner as wellunderstood in the art. The secondary coil or winding 25 shown isinclosed in a generally rectangular open ended box-like insulatingstructure of micanite or other suitable material. This structuredesignated at 32 forms an interrening insulating barrier between thesecondary winding and the outer legs 10 and base 12 of the secondarycore, as well as between this winding and the shunt to be hereinafterreferred to. This intervening insulating barrier is provided with aninsulating partition 33 which may be of similar insulating material andis disposed between the sections of the secondary coils 25.

The shunt designated in its entirety at comprises a pair of transverselylaminated stacks 36 and 37 disposed between the legs of the primary core5 adjacent the butt joint 11 and on the primary side. The butt joint. 14is adjacent the primary end of the secondary winding and the shunt pathis disposed between the legs of the primary core adjacent the butt joint14 and on the primary core side as well as between the primary andsecondary windings. For the purpose of illustration the shuntstack 36has an insulating barrier 40 between it and the adjacent outer leg 10 ofthe primary core with a similar insulating barrier 41 between theopposite end of the shunt stack 36 and the central or intermediate leg 9of the primary core and the shunt stack 37 has similar insulatingbarriers 42 and 43 between the central or intermediate leg of theprimary core and one end of the shunt stack 37 and between the oppositeend of the shunt stack and the adjacent outer leg of the primary core.These insulating barriers 40, 41, 42 and 43 which may be of red fibre orother suitable insulating material provide gaps or insulating barriersineach ot' the shunt stacks 36 and 37, it being understood that althoughthe particular arrangement shown and described in detail provides twogaps in each shunt stack, one gap or any desired number of gaps may beprovided in each shunt stack as suitable or preferred.

In operation the exciting current is applied across the desiredterminals of theprimary winding 16. This exciting current is ofrelatively high electromotive force and upon initial energization of theprimary winding substantially the entire magnetic flux threads throughthe primary and secondary cores and the relative great initial intensityin the secondary field provides a high induced initial voltage in thesecondary winding. This relatively high initial voltage in the secondarywinding is particularly desirable in the initial breaking down of orionization of the gases in a neon or other gaseous tube.

The shunt path has a reluctancehigher than the reluctance of thesecondary core so that upon initial energization of the primary windingsubstantially the entire magnetic flux threads through the secondarycore to provide the high initial voltage in the secondary winding asreferred to and then upon energization of the secondary coil or winding,the opposition set. up increases the reluctance of the secondary coreand thereafter the amount of flux required to saturate the secondarycore. Upon energization of the secondary winding the increase inreluctance of the secondary core with the decrease in the amount of fluxrequired to saturate the same causes the magnetic flux threading throughthe primary core to break down'or overcome the reluctance of-the shuntpath and at least a part of the primary flux leaks through the shuntpath 35 and threads back through the primary core. As already pointedout the flux threading through and intensity of the secondary field isthereby reduced with an accompanying reduction in the voltage in thesecondary winding below the relatively high initial voltage. This isparticularly desirable in connection with gaseous tubes and the likewhere a relatively high initial voltage is required and thereafter thevoltage required to operate or maintain the tube lighted is less.

As already pointed out the device may be designed to proportion asdesired the leakage back through the shunt path with respect to the fluxwhich threads through the secondary core, by means of which the voltagewhich follows the relatively high initial voltage may be reduced asdesired and effectively controlled.

The cross section of the secondary core (5 is preferably less than thatof the primary core. This smaller section in the secondary core-may beconveniently provided in the embodiment illustrated b stacking fewer laminations in the secon my core than in the primary core and blocking thereduced height of the secondary core 6 up to the height of the primarycore by means of suitable blocks or strips of wood or other suitableinsulating material. The reduction in section of the secondary core notonly results in saturating the secondary core to provide a high inducedinitial voltage and decreases the flux required to saturate thesecondary core but apparently decreases the amount of flux which isshunted through the shunt path 35 upon energization of the secondarywinding. This enables a reduction in the section of the shunt 35 whichreduces the space between the primary and secondary windings andincreases the space allowed for these windings in a device of givensize. The size of the windings may thereby be increased. The resultingdevice is exceedingly compact and the cost is reduced.

In the particular device illustrated the core laminations arestandardized, that is the same laminations are employed in both theprimary and secondary cores and these laminations may be standardizedwith the core laminations of transformers of other types. As alreadypointed out the transformer of the present invention is not limited toany particular use or purpose but may .be employed asand where suitableor desired and may be made up in any desired size.

In the particular embodiment shown the laminations of both the primaryand secondary cores are clamped on each side between a pair of clampbars or brackets 60. These bars or brackets may be of angle ironformation, as shown, and their opposite ends project beyond the closedend of the primary core at one end and beyond the closed end of thesecondary core at the opposite end. These projecting ends of the bars orbrackets 60 are provided with registering apertures through which extendclamping bolts 62, each provided with a head engageable with one bar orbracket 60 and having threaded engagement beyond the other bar orbracket with a suitnut 63 for clamping and securing the as-. sembledcore laminations together. The blocks or strips 50 block the secondarycore up to the same height as the primary core and the bars or brackets60 form a common clamping frame for both cores of the transformer andfor binding the two cores together into a unitary device. I

The shunt stacks 36 and 37 may have pressed fit between the legs of theprimary core 5 or they may be otherwise mounted therebetween. Thepressed fit of the shunt stacks 36 and 37enables conveniently adjustingthe position of these stacks between the legs of the primary core whichprovides a convenient adjustment for adjusting and rating the device.

The transformer may be arranged in any suitable casing or housing whichhas been omitted for the sake of clarity and it may be mounted'uponmetal brackets or adjacent external magnetic materials without beingaffected thereby and without any undesirable variation in the actionoroperation of the de-' vice.

leg of the secondary core may be of a width less than the width of thecentral leg of the primary core and where there is a shunt it may be adjustably held ire-Other manners than by means of the pressed fit shown.

It is to be still further understood that the larger cross sectionprimary may be employed I with the smaller cross section secondary withthe shunt. In this case the greater density in the secondary willprovide a self compensa tion by a flux leakage to atmosphere instead ofthru the shunt between the legs of the primary.

With the arrangement illustrated the entire shunt is in the primary andthe gap or butt joint between the legsof the primary and secondary coreslies in a common transverse plane.

We claim 1. In a transformer having a primary coil for connection withthe exciting current, a secondary, primary and secondary cores, andmeans in said transformer for inducing a relatively high initial voltagein the secondary and for thereafter decreasing the voltage in thesecondary, said means including a shunt pathin the primary core and abutt joint between the primary and secondary cores adjacent said shuntand on the secondary side thereof. I

" 2. In a transformer having a primary coil for connection with thecurrent supply, a secondary, a primary core, a secondarycore having across section less than that of the primary core, a butt joint betweentlifeprh.

mary and secondary cores, and a shunt be tween the legs of the primarycore adjacent said joint and on the primary core side.

3. In a transformer having primary and secondary coils, the combinationof a primaryv core, a secondary core, a butt joint between' 5 followingenergization of the secondary coil.

5. In a transformer having primary and secondary CO1lS, the combinationof a primary core, a secondary core havin a cross section less than thecross section of t e primary core,

a butt joint between the primary and secondary cores, a shunt adjacentsaid joint and on the primary side thereof for shunting the primary fluxback through the primary core -following energization o the secondarycoil, and a gap in said shunt increasing the open circuit reluctance ofthe shunt be 0nd the open circuit reluctance of the secon ary core.

6. A transformer comprising primary and secondary coils having separatelaminated cores therefor, said cores having central and enclosing le sin register and in butt contact and a shunt between the enclosing andcentral legs of'the primary core adjacent said butt contact and on theprimary side, said shunt having an open circuit reluctance reater thanthe open circuit reluctance of t e secondary core.

7. A transformer comprising a laminated primary core, a laminatedsecondary core of a cross section less than that of the primary core,said cores having central and enclosing legs in register and in buttcontact and a shunt between the enclosing and central legs of theprimary core adjacent said butt contact and on the primary side, saidshunt having an open circuit reluctance greater than the open circuitreluctance of the secondary core.

8. A transformer comprising primary and secondary coils. a laminatedprimary core, a laminated secondary core of a cross section less thanthat of the primary core, said cores having central and enclosing legsin register and in butt contact and a shunt between the enclosing andcentral legs of the primary core adjacent said butt contact and on theprimary side, said shunt having an open circuit reluctance greater thanthe open circuit reluctance of the secondary core.

9. A transformer comprising primary and secondary coils, a laminatedprimary core, a laminated secondary core of a cross section less thanthat of the primary core, said cores having central and enclosing legsis register and in butt contact and a shunt between the enclosing andcentral legs of the primary core adjacent said butt contact and on theprimary side, said shunt having an open circuit reluctance greater thanthe open circuit reluctance of the secondar comprising laminated s iuntstacks interposed between the outer and central legs of the primary coreand each insulated at its opposite ends from said legs.

10. A transformer comprising primary and secondary coils, a laminatedprimary core, a laminated secondary core of a cross section less thanthat of the primary core, said cores having central and enclosing legsin register and in butt contact and a shunt between the enclosing andcentral legs of the primary core adjacent said butt contact and on theprimary side, said shunt having an open circuit reluctance greater thanthe open circuit reluctance of the secondary core, said shunt comprisinglaminated shunt stacks interposed between the outer and central legs ofthe primary core and each insulated at its opposite ends from said legs,said staclts having pressed fit between said main core legs and beingadjustable therebetween.

11. in a transformer having primary and secondary coils, the combinationof a gen erally E-shaped primary core, a generally E-shaped secondarycore of a cross section less than the cross section of the primary coreand a butt joint between the legs of the cores and lying in a commontransverse plane.

12. In a transformer having primary and secondary coils, the combinationof a generally E-shaped primary core, a generally E-shaped secondarycore and a butt joint between the legs of the cores and lying in acommon transverse plane.

13. A transformer comprising primary and secondary coils, a laminatedprimary core, a laminated secondary core of a cross section less thanthat of the primary core,

said cores having registering legs in butt contact, and a shunt betweenthe legs of the primary core, said shunt having an open circuitreluctance greater than theopen circuit reluctance of the secondary coreand comprising a laminated shunt staclr interposed between the legs ofthe primary core.

1 A transformer comprising primary and secondary coils, a laminatedprimary core, a laminated secondary core of a cross section less thanthat of the primary core,

said cores having registering legs in butt contact, and a shunt betweenthe legs of the primary core, said shunt having an open circuitreluctance greater than the open circuit reluctance of the secondarycore and core, said shunt comprising a laminated shunt stack adjustablysupported between the legs or the primary core.

15. A transformer comprising primary and secondary coils, a laminated.primar core, a laminated secondary core of cross section less than thatof the primary core, said cores having registering legs in contact, anda shunt between the legs of the primary core, said shunt having a opencircuit reluctance greater than the open air cult reluctance of thesecondary core and comprising a laminated shunt stack adjust ablysupported between the legs of the primary core and raving an insulatedtherein,

' 16, In a transformer having primary and secondary coils, thecombination oi: type magnetic core having magnetic envelope completelysurrounding and. enclosing said coils and having primar core part andsecondary core part, a shunt for the primary core part and havingreluctance greater than the reluctance of the secondary core part, and abutt joint in he coil. surrounding envelope of core 7 17, in atransformer having primary and secondary coils, the combination oi shelltype magnetic core having a mafinetic enva lope completely surroundingenclosing said coils and having primary core and. a secondary core part,a shunt for the primary core part and having a reluct n greater than thereluctance of the secon my core part, and a in said shunt increas r. theopen. circuit reluctance oi? the shunt beyond the open. circuitreluctance o'lrthe see ondary core part.

18. A transformer y comprising pair of laminated magnetic core stacks,having inner confined and outer enclosing legs in register and in buttcontact, primary and secondary coils surrounding the inner con finedlegs of said core stacks, and an internal and confined shunt between theinner confined and outer enclosing legs of one core stack.

1 A transformer, comprisinga of laminated manetic core stacks, each hawing inner conhned and outer enclosing legs in register and in buttcontact, said core stacks forming primary and econdary core parts,primary and secondary coils surround ing the inner confined legs of saidcore stacks, and an internal and confined shunt between the innerconfined and outer enclosing legs-oi one core, said shunt having an opencircuit reluctance greater than the open circuit reluctance or thesecondary core part, I

20, in a transformer having primary secondary coils, the combination ota pair of cores each having a pair of outer coil enclosing legs and aninner intermediate leg,

til

butt

lllll a base connecting the outer and inner legs at the outer end ofeach core and completing the coil enclosure, said outer and inner legsof each core being open at the inner ends of the cores, and a butt jointbetween the inner open ends of the inner and outer legs of said cores,and lying in a common transverse plane.

21. In a transformer having primary and secondary coils, the combinationof a pair of generally E-shaped cores, inverted with reference to eachother and each having a pair of outer and an intermediate leg closed atthe outer endsand open and in register at the inner ends of the coreswith a butt 4 joint between the inner ends of saidouter and inner legs,and lying in a common trans verse lane.

22. n a transformer having primary and secondary coils, the combinationof a core comprising a pair of laminated core stacks each having a baseortion and inner confined and outer enclosing legs extending from thebase portions, said stacks being assembled in inverted relation withrespect to each other with the base portions of the respective stacks atopposite ends of the core to form with the outer legs of the stacks asurrounding magnetic envelope and with the ends of the inner and outerlegs in register and in butt contact.

23. In a transformer, the combination of a pair of laminated core stackseach having a base portion with inner confined and outer enclosing legmeans extending from said base portions, said stacks being assembled ininverted relation with respect to each other with the base portions ofthe respective stacks at opposite ends of the core to form with theouter legs of the stacks a surrounding magnetic envelope and with theends of the inner and outer leg means in register and in butt contact, apair of secondary coil parts.

surrounding the inner leg means and enclosed by the outer leg means, aground connection between said secondary coil parts and a primary coilalso surrounding the central leg means and enclosed by the outer legmeans.

24. In a transformer, a core comprising a pair of laminated core stackseach having a base portion with inner confined and outer I enclosinglegs extending therefrom, said stacks being assembled in invertedrelation with respect to each other with the base portions of therespective stacks at opposite ends of the core to form with the outerlegs of the stacks a surrounding magnetic envelope and with the ends ofthe inner and outer legs in register and in butt contact, and means forclamping the laminations of the stacks together and for holding the twostacks in assembled relation withrespe'ct to each other.

25. In a transformer, a core comprising a pair of laminated core stackseach having a base portion with inner confined and outer enclosing legsextending therefrom, said stacks being assembled in inverted relationwith respect to each other with the base portions of the respectivestacks at opposite ends of the core to form with the out-er legs of thestacks a surrounding magnetic envelope and with the ends of the innerand outer legs in register and in butt contact, means for clamping thelaminations of the stacks together and for' holding the two stacks inassembled relation with respect to each other, said means comprisingclamping means extending along the top of the core, clamping meansextending along the bottom of the core, and means for clamping saidmeans together with the core stacks assembled therebetween.

26. In a transformer, the combination of a core having outer enclosingand inner leg means, a pair of stationary secondary coil partssurrounding the central leg means and enclosed by the outer leg means, aground connection between the secondary coil parts, a primary coil alsosurrounding the central leg means and enclosed by the outer leg means,and stationary shunt means disposed between said central and outer legmeans for reducing the voltage in the secondary coil means by saturationof the magnetic core.

In witness whereof, we hereunto subscribe our names this 8th day ofNovember, 1927.

' JAMES C. DALEY.

EDWIN G. GODDARD.

